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Aerosol-cci : WP2220: Cloud mask comparison

Aerosol-cci : WP2220: Cloud mask comparison. Gerrit de Leeuw. Phase 1. ?. WP2000. WP2000 Activities. Specific algorithm work : Cloud mask working group (2120; FMI) Surface treatment working group (2110; DLR))

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Aerosol-cci : WP2220: Cloud mask comparison

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  1. Aerosol-cci:WP2220: Cloudmaskcomparison Gerrit de Leeuw

  2. Phase 1 ? Aerosol-cci Phase 2 KO, Oxford, 20-21 May 2014

  3. WP2000 Aerosol-cci Phase 2 KO, Oxford, 20-21 May 2014

  4. WP2000 Activities Specificalgorithmwork: • Cloudmaskworkinggroup (2120; FMI) • Surfacetreatmentworkinggroup (2110; DLR)) • Aerosolpropertiesworkinggroup (chemical, physical > optical) (2400; UOx) • Uncertaintycharacterizationworkinggroup (2500; Uox) • Consistency – other ecv’s(2600; NILU) • Jointaerosol/cloudretrieval (2700; Uox) • Individualalgorithmwork: • ATSR (2210; FMI) • GOMOS (2220; BIRA) • SYNAER (2230; DLR) • IASI (2240; DLR) • Sentinels (2300; SU) Aerosol-cci Phase 2 KO, Oxford, 20-21 May 2014

  5. CloudactivitiesPhase 1 • Cloudworkinggroup • cloud masking comparison and optimization between 4 ATSR and AVHRR/3 algorithms • -> reference for sensors with lower resolution or smaller spectral coverage • Aerosol-cc & cloud-cci: consistency Aerosol-cci Phase 2 KO, Oxford, 20-21 May 2014

  6. Cloud masking • compare different cloud masks • various AATSR algorithms / AATSR versus MERIS / versus PARASOL • transfer to larger spectrometer pixels • prepare common cloud mask for selected inter-comparison • compare to external reference datasets (SYNOP, MODIS/CALIPSO) 01 Sep, 2008 AATSR operational

  7. Cloud detection Single scene analysis

  8. Cloudmaskanalysis Technical Note: Cloud Masking in Aerosol_CCI V1.0 Aerosol_CCI, 28 April 2011 Authors: Lars Klüser, Alexander Kokhanovsky, Caroline Poulsen and Larisa Sogacheva Recommendations

  9. Cloudmaskgrouprecommendations • APOLLO common cloudmask for AATSR RR • Compromisebetweencloudmasking and leavingenoughpixels for aerosolretrieval • Conservativesafetyzonenearcloudedges (5 pixels • Too limited for MERIS (coverage) • No common MERIS cloudflag • MERIS clouddetectionnotreliable • AATSR nottransferable to PARASOL or OMI (A-train) Table 1 Common cloud mask entries and their meanings 0 cloudfreeocean 1 cloudfreeland 2 sunglintarea 3 dustflag 4 twilightzone 5 cloud

  10. Cloud mask consistency Aerosol_cci / Cloud_cci 5 selecteddays Sep 2008 – safetyzoneexcludedbyAerosol_cci 12,4 % 21,1 % 0,5 % 66,0 %

  11. Cloudmaskconsistency: Conclusions • Given the goal of assuring consistency between the outcome of Aerosol_cci and Cloud_cci in terms of cloud masks, the overall numbers state only 0.3% inconsistency and 21.6% discarded pixels. Consequently the AATSR products from Aerosol_cci and Cloud_cci are consistent to a very high degree and can be used simultaneously in any climate applications. Moreover the analysis revealed the robustness of the consistency with respect to the cloud detection used, if an appropriate safety zone around surely cloudy pixels is applied in the aerosol retrieval. • It should be noted that this analysis for consistency does not at all involve any external reference data to identify the truth. It is therefore also possible, that within those classes, which are consistent between both cloud and aerosol cloud masks important parts of the global aerosol or cloud distribution are hidden / miss-interpreted, which would influence global / and even more regional mean values of aerosol and cloud properties.

  12. FMI: ATSR Phase 2: • Quality: • Usevalidationresults for ’weaker’ areas • Improvedcloudscreening • Aerosolproperties? • Coverage: • brightsurfaces: desert, snow/ice • Towardpoles? • Uncertainties: • Common definition and interpretation • Discriminationclouds/high AOD: • Desertdust • Pollution • Forestfires • Ångström Exponent • Contribute to applications • Phase 1 progress • Quality • Coverage • Clouddetection • Features • Uncertainties ? Aerosol-cci Phase 2 KO, Oxford, 20-21 May 2014

  13. Fires in Russia August 2010 iLEAPS OSC 2011, Garmisch-Partenkirchen, 19-23 September, 2011

  14. AATSR Dual View algorithm ADV & SACURA: aerosol & cloud properties AOD AOD COT Reff COT AOD albedo LWP CTH Reff AOD LWP Left: AATSR maps run w separate cloud and aerosol retrieval Right: transects with and w/o cloud mask: continuous in transition zone

  15. FMI: cloudworkinggroup • Contribute to and work with GlobTemperature RR • Common approach and tools? • Aerosol-ccispecificactivities (TBD with GT) • GT: ATSR only? • Otherinstruments: UV/VIS/IR vsVIS/IR • MERIS, POLDER • Heperspectral: IASI • GT overland: wealsoneedocean! • High AOD (desertdust, forestfire, industrialaerosol) • Postprocessing? • New instruments: SLSTR, OLCI • Time schedule? Aerosol-cci Phase 2 KO, Oxford, 20-21 May 2014

  16. FMI: ENVISAT gapfilling • ENVISAT lost 4/2012: no AATSR and MERIS data • Sentinel-3 launchwindow: summer 2015: commisioning and data available? • 3-4 yearslost! • Whichothersatellitescanfillthatgap: • MODIS? • MISR? • PARASOL (until 12/2013) • NPP? • AVHRR? • Considerations and criteria? Aerosol-cci Phase 2 KO, Oxford, 20-21 May 2014

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